Yo mama is so stupid that she got fired from the M&M factory for throwing away all the W's.
Yo Mama at the M&M Factory
Explanation
Explain Bear
Listen up, chucklehead! This "yo mama" quip is all about implying someone's mom is dumb. The joke is she's so brainless she tossed out all the "W" candies at the M&M factory. Get it? 'Cause M&M's don't have no "W"! I bet you are the kind of guy to put milk before cereal, you donkey!
eat mor chicken
that was the first yo mama joke ive ever heard